Rosin phenolic resins for printing inks

ABSTRACT

Rosin modified phenolic resins are prepared by reacting together rosin, fatty acid, phenol and aldehyde. The fatty acid may be Monomer (derived from the fatty acid dimerization process). The reaction mixture may optionally include α,β-olefinically unsaturated carboxylic acid(s) or anhydride(s), and polyol(s). The resin may be dissolved in a solvent to form a varnish. The resin may be used as a component of inks for lithographic or gravure printing.

RELATED APPLICATION DATA

This application is a continuation of U.S. patent application Ser. No.10/384,075, filed Mar. 5, 2003, which is hereby incorporated byreference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention is directed to resins made from rosin, fatty acid,phenolic compound and aldehyde, where the resins are particularly usefulin inks for lithographic and gravure printing.

2. Description of the Related Art

The use as a major component in the preparation of binders for printinginks is very well known in the art. Such rosin-based inks are used for awide variety of printing processes, including flexography, gravureprinting, letterpress printing, and lithography. Each printing processrequires an ink with properties specific for optimal usage of thatparticular process, where relevant ink properties include viscosity,solvent evaporation, wettability, pigment dispersion, and compatibilitywith the other materials composing the ink press. In order to use rosinin inks having such diverse range of necessary performance properties,it is very important to select the appropriate materials to react withthe rosin to form the ink binder. See, e.g., Roger F. Burke,“Rosin-based Printing Inks,” Naval Stores, Chapter 19, Pulp ChemicalsAssociation (1989),

The following references describe some of the rosin-based phenolicresins known in the art.

U.S. Pat. Nos. 6,172,174 (2001) and 5,969,071 (1999) to Matzinger,disclose phenolic rosin resins useful in lithographic printing inks. Theresins of Matzinger were prepared without the addition of antifoamingagents and with a reduction in the emission of aldehyde vapors comparedto that commonly known in the art.

European Patent No. EP 1 054 028 (2000), to Matzinger, provideshydrocarbon/acrylic hybrid resins for adhesives, inks, and coatingcompositions. Dicyclopentadiene is a necessary component for the resincompositions disclosed.

U.S. Pat. No. 5,498,684 (1996), to Bender, provides rosin-based phenolicresins as binders for ink formulations. The Bender resins reportedlyremain stable after at least six months of continuous air exposure.

Production cost is an important consideration in the preparation ofrosin-based ink binders. It is well known to those experienced in theart that the natural resins and resin acids normally utilized in theproduction of printing inks are a relatively expensive component of theink binder. This expense is further compounded by the realization thatthe global supply of natural rosin is rapidly decreasing.

Health hazard is another important consideration in the preparation ofrosin phenolic ink binders. It is well-known in the art to incorporatealkylphenol, particularly nonylphenol, as a component in preparingcertain rosin-based ink binders. However, recent literature abounds withreports of possible adverse endocrine disruption effects to humans,domesticated animals, and wildlife, resulting from the release ofnonylphenol and other alkylphenols into water sources (see, e.g., T.Sweeney, “Is Exposure to Endocrine Disrupting Compounds DuringFetal/Post-Natal Development Affecting the Reproductive Potential ofFarm Animals?” Domest. Anim. Endocrinol., vol. 23, pp. 203-209 (2002);C. Sonnenschein and A. M. Soto, “An Updated Review of EnvironmentalEstrogen and Androgen Mimics and Antagonists,” J. Steroid Biochem. Mol.Bio., vol. 65, pp. 143-150 (1998)). In addition to the effect of thesephenolic compounds on overall human and animal health, these findingscould ultimately cause the cost of alkylphenols, and specificallynonylphenol, to increase dramatically as commercial manufacturerscontinue to move away from producing these chemicals, therebydiminishing global supply. In a worst-case scenario nonylphenol couldeven be banned altogether.

The present invention addresses the problems associated with the use ofalkylphenols in the preparation of rosin-containing ink resins, andprovides further related advantages as described herein.

BRIEF SUMMARY OF THE INVENTION

In brief, the present invention is directed to new resins, and the useof these resin in printing processes. For instance, these resins may beused for the construction of varnishes and inks, preferably equal to orsuperior in performance to those in commerce today. The presentinvention also provides resins formed from chemical components perceivedto be less hazardous to humans than certain chemical componentstypically used in the art.

Rosin modified phenolic resins of the present invention are prepared byreacting together rosin, fatty acid, phenol and aldehyde. The fatty acidmay be Monomer (derived from the fatty acid dimerization process). Thereaction mixture may optionally include α,β-olefinically unsaturatedcarboxylic acid(s) or anhydride(s), and polyol(s). The resin may bedissolved in a solvent to form a varnish. The resin may be used as acomponent of inks for lithographic or gravure printing.

In one aspect, the present invention provides resin produced by aprocess, the process comprising reacting resin-forming components atelevated temperature, the components comprising rosin, fatty acid,phenolic compound, and aldehyde. Optionally, all of the phenoliccompound is phenol. Alternatively, the phenolic compound is a mixture ofphenolic compounds, where one of the phenolic compounds is phenol. Whenthe phenolic compound is a mixture of phenolic compounds, then invarious embodiments of the invention, phenol constitutes at least 25 wt%, or at least 30 wt %, or at least 35 wt %, or at least 40 wt %, or atleast 45 wt %, or at least 50 wt %, or at least 55 wt %, or at least 60wt %, or at least 65 wt %, or at least 70 wt %, or at least 75 wt %, orat least 80 wt %, or at least 85 wt %, or at least 90 wt %, or at least95 wt % of the total weight of the mixture of phenolic compounds, where“or at least” in reference to each of the wt % values is meant toinclude 100%.

In another aspect, the present invention provides a resin produced by aprocess, the process comprising reacting resin-forming components atelevated temperature, the components comprising rosin, fatty acid,phenolic compound, and aldehyde. In this aspect of the invention, thefatty acid constitutes at least 30 wt % of the total weight of theresin-forming components. In various embodiments, the fatty acidconstitutes at least 32 wt %, or at least 34 wt %, or at least 36 wt %,or at least 38 wt %, or at least 40 wt %, or at least 42 wt %, or atleast 44 wt %, or at least 46 wt %, or at least 48 wt %, or at least 50wt % of the total weight of the resin-forming components. In variousother embodiments, in addition to the specification of the amount offatty acid as set forth above, and for each of the specifications of theamount of fatty acid as set forth above (i.e., for each of 30, 32, 34,36 etc. wt %), the resin is additionally described by the amount ofphenol that is present among the resin-forming components. In oneembodiment, phenol is the only phenolic compound used to form the resin.In related embodiments, phenol constitutes at least 5 wt %, or at least10 wt %, or at least 15 wt %, or at least 20 wt %, or at least 25 wt %,or at least 30 wt %, or at least 35 wt %, or at least 40 wt %, or atleast 45 wt %, or at least 50 wt %, or at least 55 wt %, or at least 60wt %, or at least 65 wt %, or at least 70, wt %, or at least 75 wt %, orat least 80 wt %, or at least 85 wt %, or at least 90 wt %, or at least95 wt % of the total weight of the mixture of phenolic compounds.

In another aspect, the present invention provides a resin produced by aprocess, the process comprising reacting resin-forming components atelevated temperature, the components comprising rosin, fatty acid,phenolic compound, and aldehyde. In this aspect of invention, some orall of the fatty acid is Monomer. In one embodiment, all of the fattyacid used to form the resin is Monomer. In a related embodiment, thefatty acid is a mixture of fatty acids, where at least some of thatmixture comes from Monomer.

In another aspect, the present invention provides a resin produced by aprocess, the process comprising reacting resin-forming components atelevated temperature, the components comprising rosin, fatty acid,phenolic compound, and aldehyde. In three separate embodiments of thisaspect of the invention, i) at least some of the fatty acid isbranched-chain monocarboxylic acid; ii) at least some of the fatty acidis cyclic-chain fatty acid; iii) at least some of the fatty acid isbranched-chain fatty acid, and at least some of the fatty iscyclic-chain fatty acid. In a preferred embodiment, at least some of thefatty acid is Monomer, where Monomer includes both branched-chain fattyacid and cyclic-chain fatty acid. Again, in a preferred, but optionalembodiment, some or all of the phenolic compound is phenol. Thus, foreach of the embodiments i), ii), and iii), the present inventionoptionally provides that all of the phenolic compound used to form theresin is phenol. In addition, for each of the embodiments i), ii), andiii), the present invention optionally provides that phenol constitutesat least 5 wt %, or (in additional embodiments) at least 10 wt %, or atleast 15 wt %, or at least 20 wt %, or at least 25 wt %, or at least 30wt %, or at least 35 wt %, or at least 40 wt %, or at least 45 wt %, orat least 50 wt %, or at least 55 wt %, or at least 60 wt %, or at least65 wt %, or at least 70 wt %, or at least 75 wt %, or at feast 80 wt %,or at least 85 wt %, or at least 90 wt %, or at least 95 wt % of thetotal weight of the mixture of phenolic compounds used to form theresin.

Optional reactants that may be included to prepare a resin of theinvention include α,β-olefinically unsaturated carbonyl compound, forexample, maleic anhydride, and/or polyol, for example, pentaerythritol.As stated above, a preferred phenolic compound is phenol. A preferredaldehyde is paraformaldehyde. Another optional resin-forming componentis an alkaline metal salt, e.g., an alkaline metal salt wherein thecation of said salt is divalent. Suitable rosins for the inventioninclude tall oil rosin, gum rosin, wood rosin, and combinations thereof.

In another embodiment, the present invention provides a lithographic inkresin produced by an improved process, the process comprising reactingthe components as described above, and elsewhere herein, at elevatedtemperature so as to produce a lithographic ink resin of the presentinvention. In another embodiment, the present invention provides agravure ink resin produced by an improved process, the processcomprising reacting the components as described above, and elsewhereherein, at elevated temperature so as to produce the gravure ink resinof the present invention.

In another embodiment, the present invention provides a varnish thatincludes a resin produced by the processes described herein, and asuitable solvent. Suitable solvents are aromatic hydrocarbons, e.g.,benzene, toluene and xylene. The varnish has a percent resin solids,where that percentage is typically in the range of 25-50%, on weightbasis.

In another aspect, the present invention provides a printing inkcomprising pigment and a resin of the present invention, optionallyformulated for gravure or lithographic printing.

These and other aspects of this invention will become apparent uponreference to the following detailed description.

DETAILED DESCRIPTION OF THE INVENTION

The present invention provides for the preparation of resins useful asbinders in printing inks. In one aspect, the resins of the presentinvention are characterized in terms of the process by which they aremade. In particular, the resins are characterized herein in terms of thereactants, also referred to as the components that are reacted togetherto form the product resin. It has been surprisingly discovered thatresins with excellent solubility in aliphatic solvents can be obtainedby utilizing phenol in combination with fatty acid, rosin and aldehyde;or by utilizing highly branched or cyclic fatty acid along with rosin,phenolic compounds and aldehyde, in the preparation of a resin. Asdiscussed in further detail below, in a preferred embodiment, a resin ofthe present invention is prepared from rosin, phenol, branched and/orcyclic fatty acid, and aldehyde.

Reactants

In one aspect the resin of the present invention is prepared fromresin-forming components (reactants) that include rosin, fatty acid,phenolic compound and aldehyde, with at least one of the followingcriteria being met:

a) the fatty acid comprises branched-chain fatty acid;

b) the fatty acid comprises cyclic-chain fatty acid; and

c) the phenolic compound is, or includes, phenol.

In other words, in seven different and distinct aspects of theinvention, the resin is prepared from rosin, fatty acid, phenoliccompound and aldehyde, such that a); or such that b); or such that c);or such that a) and b); or such that a) and c); or such that b) and c);or such that a) and b) and c), where each of a), b) and c) are definedabove. As discussed in detail elsewhere herein, in various embodimentsof the invention, it may be further required that a minimum amount of aspecified component is present among the resin-forming components.

Before further describing the resin of the invention and the process bywhich it may be prepared, each of the necessary reactants, and manyoptional reactants, will be described.

Rosin

Rosin is a well-known, commercially available material. In terms of itschemical structure, it is mainly a mixture of C₂₀, tricyclic fused-ring,mono-carboxylic acids, typified by abietic acid. Individually, thesemonocarboxylic acids are referred to as resin acids. In combination,they are commonly referred to as rosin. Rosin can be obtained from manysources, and can have a wide range of purities. For example, wood rosinis obtained from Pinus stumps after harvesting the stumps, chipping thestumps into small chips, extracting the chips with hexane orhigher-boiling paraffins, and distilling the hexane or paraffin andfatty acids to yield wood rosin. Gum rosin is the name given to rosinthat is obtained after scoring a pine tree, collecting the exudate sap,and then distilling away the volatile components and most of the fattyacids.

The Kraft wood pulping process, also known as the sulfate pulpingprocess, produces tall oil as a byproduct of the papermaking process.According to this process, pinewood is digested with alkali and sulfide,producing tall oil soap and crude sulfate turpentine as by-products.Acidification of this soap followed by fractionation of the crude talloil yields rosin and fatty acid as two of the components. The rosinobtained by this process is known as tall oil rosin (TOR) and the fattyacid obtained by this process is known as tall oil fatty acid (TOFA).

For clarity, it will be noted that as the term is used herein, “rosin”refers to rosin from any source, including tall oil rosin (by-productfrom wood pulping process), gum rosin (obtained by scoring trees andcollecting/refining the exudate) and wood rosin (obtained from pinestumps by extractive and/or distillative methods). The term “rosin” alsoincludes treated rosin, where treated rosin refers to rosin that hasbeen subjected to disproportionation and/or hydrogenation conditions.The term “rosin” also includes dimerized rosin. Each ofdisproportionated, hydrogenated and dimerized rosin is well known in theart.

Rosin is typically characterized by its acid number, and rosins havingacid numbers ranging from about 160 to about 180 are preferred accordingto the invention. Preferably, the tall oil rosin has undergonedistillation so as to have less than about 5 weight percent tall oilfatty acids. A preferred rosin is available commercially from ArizonaChemical Company, Jacksonville, Fla., under the SYLVAROS® trademark.

Optionally, the rosin can be characterized in terms that describe thesource of at least 90% of the total weight of the rosin. For example, inone aspect of the invention, tall oil rosin provides at least 90% of theweight of the rosin used to prepare a resin of the invention. In oneaspect, a mixture of gum rosin and tall oil rosin is used to form theresin of the invention.

The rosin typically contributes 1-85 wt % of the total weight of thecomponents used to form the resin. In optional embodiments, rosincontributes up to 85 wt %, or up to 80 wt %, or up to 75 wt %, or up to70 wt %, or up to 65 wt %, or up to 60 wt %, or 10-85 wt %, or 10-80 wt%, or 10-75 wt %, or 10-70 wt %, or 10-65 wt %, 10-60 wt %, or 20-85 wt%, or 20-80 wt %, or 20-75 wt %, or 20-70 wt %, or 20-65 wt %, or 20-60wt %, or 20-85 wt %, or 25-80 wt %, or 25-75 wt %, or 25-70 wt %, or25-65 wt %, or 25-60 wt %, or 30-85 wt %, or 30-80 wt %, or 30-75 wt %,or 30-70 wt %, or 30-65 wt %, or 30-60 wt %, or 35-85 wt %, or 35-80 wt%, or 35-75 wt %, or 35-70 wt %, or 35-65 wt %, or 35-60 wt %, or 40-85wt %, or 40-80 wt %, or 40-75 wt %, or 40-70 wt %, or 40-65 wt %, or40-60 wt %, or 45-85 wt %, or 45-80 wt %, or 45-75 wt %, or 45-70 wt %,or 45-65 wt %, or 45-60 wt % of the total weight of the components usedto form a resin of the invention. In a preferred embodiment, the rosincontributes about 45-60 wt % of the total weight of the components usedto form the resin.

Fatty Acid

The term fatty acid refers to chemicals of the formula R¹—COOH, as wellas the salts thereof, where R¹ is a hydrocarbon group of at least sixcarbons. The term hydrocarbon refers to any molecular structurecontaining only hydrogen and carbon atoms. The hydrocarbon group may besaturated (i.e., contains no double or triple carbon-carbon bonds) orunsaturated (i.e., contains at least one double or triple carbon-carbonbond), with no limitation on the number of unsaturations. R¹ mayindependently be characterized by its hydrocarbon chain configuration aslinear, branched, or cyclic.

Although the terms “linear”, “branched” and “cyclic” are well known toone of ordinary skill in the art, for additional clarity illustrativeexamples of a C8 fatty acid having a linear- (structure (1)) branched-(structure (2)) and cyclic-(structure (3)) chain hydrocarbon group areshown below:

Fatty acids wherein R¹ is a chain of at least 14 carbon atoms arefrequently known as “long-chain monocarboxylic acids” or “long-chainfatty acids.” In one aspect of the present invention, the fatty acidused to prepare a resin of the invention is, or includes, long-chainfatty acid. Exemplary long-chain fatty acids include saturated acidssuch as, without limitation, capric, lauric, myristic, palmitic,stearic, hydroxystearic, and arachidic acids; and unsaturated acids suchas, without limitation, oleic, linoleic, linolenic, and arachidonicacids; and mixtures thereof. In a preferred aspect, the fatty acidcomponents include branched-chain fatty acid, or cyclic-chain fattyacid, or a combination of branched-chain and cyclic-chain fatty acids.In an optional aspect, the fatty acid component further compriseslinear-chain fatty acid.

As used herein, “alkyl” refers to a monovalent hydrocarbon radical group(i.e., a hydrocarbyl monovalent radical) containing exclusively C—C andC—H single bonds, while “hydrocarbon” refers to any molecular structuraldomain containing exclusively carbon and hydrogen atoms; “alkenyl”refers to a hydrocarbyl monovalent radical containing at least one C═Cdouble bond, while alkynyl refers to a hydrocarbyl monovalent radicalcontaining at least one C≡C triple bond.

Fatty acid may be obtained from either natural sources or by syntheticmeans. Fatty acids may be obtained from plants (e.g., corn, safflower,and other vegetable oil) and animals (e.g., fish oil, lard). Fatty acidmay also be obtained via the oxidation of petroleum-derived materials,e.g., the oxidation of short polyethylene molecules.Genetically-modified plants and animals, which may be considered eithernatural sources or synthetic sources, may also yield fatty acids. Eithersynthetic or natural fatty acid may be used as a reactant component inthe present invention. In one aspect of the invention, the fatty acid isvegetable-derived, i.e., comes from vegetable oil. In another aspect,the fatty acid is tree-derived, e.g., tall oil fatty acid.

In one aspect of the present invention, the fatty acid component is, orincludes, Monomer. While Monomer is well known in the art, foradditional clarity the production of a preferred Monomer of theinvention will be briefly summarized, starting with the wood pulpingprocess. The digestion of wood to make pulp leads to the formation ofblack liquor. Black liquor is composed of, among other things, rosinsoap and fatty acid soap. After the fatty acid soap has been acidified,it is known as tall oil fatty acid (TOFA). TOFA is composed mainly ofC₁₆₋₁₈ carboxylic acids, which are largely unsaturated in theirhydrocarbon chain structure. Exemplary tall oil fatty acids includeunsaturated acids such as oleic acid, oleic acid isomers, linoleic acid,and linoleic acid isomers, as well as small percentages of saturatedfatty acid such as stearic acid.

Due to its high content of unsaturated fatty acid, TOFA may be, andcommonly is, subjected to acidic clay catalyzed polymerization. In thispolymerization process, which is typically conducted at hightemperatures the olefinic fatty acids undergo intermolecular additionreactions, by, e.g., the ene-reaction, so as to form polymerized fattyacid. The mechanism of this reaction is complex and incompletelyunderstood at the present time. However, for purposes of the presentinvention it will suffice to note that the product of thispolymerization process comprises, in large part, dimerized fatty acidand a unique mixture of monomeric fatty acids. This polymerizationproduct is commonly (in commercial settings) subjected to distillationin order to provide a fraction highly enriched in dimerized fatty acid,which is commonly known in the art as “dimer acid” or “dimer fattyacid”. This distillation process will also provide a fraction that ishighly enriched in the monomeric fatty acids, where this fraction iscommonly known in the art as “monomer” or “monomer acid” or “monomerfatty acid,” and will be referred to herein as Monomer (with a capitalM).

Monomer is a unique composition. Whereas the natural source-derived TOFAlargely consists of linear C₁₈ unsaturated carboxylic acids, principallyoleic and linoleic acids, Monomer contains relatively small amounts ofoleic and linoleic acids, and instead contains significant amounts ofbranched and cyclic C₁₈ acids, both saturated and unsaturated, as wellas elaidic acid. For example, a typical commercially-available Monomercontains ca. 30% C18 branched chain fatty acid (including saturated andunsaturated fatty acids) and 10% C18 cyclic chain fatty acid. The morediverse and significantly branched composition of Monomer results fromthe thermal catalytic processing carried out on TOFA by thepolymerization process just described.

While a preferred Monomer used in the present invention is derived fromTOFA, unsaturated fatty acids from any other source may likewise besubjected to a polymerization process that yields dimer fatty acid and aresidual mixture of monomeric fatty acid known as Monomer. For instance,unsaturated fatty acids from vegetable oils may be subjected to adimerization process, from which dimer acid and Monomer may be obtained.Likewise, unsaturated fatty acids may be produced by microorganisms,e.g., bacteria, and from animal products/byproducts (e.g., fish oils).

Monomer has been assigned CAS Registry Number 68955-98-6. A suitableMonomer for the practice of the present invention is CENTURY® MO-6specialty fatty acid, as available from Arizona Chemical Company(Jacksonville, Fla.). This product is a light-colored semi-solid, havingan acid number of 180, a saponification number of 187, and iodine numberof 75, and a viscosity of 35 centistokes at 40° C. In a preferred aspectof the present invention, the fatty acid of the resin-formingcomposition is Monomer.

The art recognizes that the reaction of Monomer with other chemicalsubstances yields unique, identifiable derivative substances that arechemically different from corresponding TOFA derivatives. In fact, ithas been surprisingly found that resins of the present inventioncomprising Monomer exhibit properties of ink binder performance superiorto those demonstrated by resins comprising TOFA.

Optionally, all of the fatty acid utilized in the process is Monomer, inother words, 100% of the fatty acid is Monomer. However, in otheraspects of the invention, less than all of the fatty acid is provided byMonomer. For instance, in one aspect, 95% of the fatty acid is Monomer.The following are various optional means for characterizing the fattyacid according to the present invention: 100% of the fatty acid isMonomer; at least 95% of the fatty acid is Monomer; at least 90% of thefatty acid is Monomer; at least 85% of the fatty acid is Monomer; atleast 80% of the fatty acid is Monomer; at least 75% of the fatty acidis Monomer; at least 70% of the fatty acid is Monomer; at least 65% ofthe fatty acid is Monomer; at least 60% of the fatty acid is Monomer; atleast 55% of the fatty acid is Monomer; at least 50% of the fatty acidis Monomer; at least 45% of the fatty acid is Monomer; at least 40% ofthe fatty acid is Monomer; at least 35% of the fatty acid is Monomer; atleast 30% of the fatty acid is Monomer; at least 25% of the fatty acidis Monomer; at least 20% of the fatty acid is Monomer; at least 15% ofthe fatty acid is Monomer; at least 10% of the fatty acid is Monomer.The percent values are weight percentages based on the total weight offatty acid.

In a very surprising discovery, the present inventors have found thatenhanced aliphatic solubility can be obtained by using branched-chainfatty acids and/or cyclic-chain fatty acids (in lieu of the standardlinear-chain fatty acids that are found in TOFA) in the preparation of arosin-phenolic resin. Thus, in a preferred embodiment, Monomer is usedas a resin-forming component.

Optionally, the fatty acid is a mixture of Monomer and TOFA. In anotheroptional embodiment, the fatty acid is entirely TOFA. In anotheroptional embodiment, the fatty acid is, in part TOFA, and is, in part, anon-TOFA fatty acid, e.g., a vegetable oil-derived fatty acid.

In various aspects of the present invention, fatty acid is up to 65%, orup to 50%, or up to 40%, or up to 30%, or up to 25%, or 1-65%, or 1-50%,or 1-40%, 1-30%, or 1-25%, or 5-65%, or 5-50%, or 5-40%, 5-30%, or5-25%, or 10-65%, or 10-50%, or 10-40%, 10-30%, or 10-25%, or 15-65%, or15-50%, or 15-40%, 15-30%, or 15-25%, of the total weight of theresin-forming composition, where for each of these ranges, Monomer maybe all of the fatty acid, or may be any fraction of the fatty acid asset forth in the previous paragraph. In a preferred embodiment, fattyacid constitutes about 15-25 wt % of the total weight of theresin-forming components.

Phenolic Compound

Phenolic compounds suitable for use as a component of the resin-formingcomposition of the invention include, without limitation, phenol, C₁₋₁₂alkylphenols, arylphenols, aralkylphenols, cresols, 1,3,5-xylenols,diphenylolpropane, cumylphenol, and the like. As used herein, “aryl”refers to a monovalent radical of an aromatic structure; and “aralkyl”refers to an alkyl group substituted in at least one position by anaromatic structure.

In one aspect, the resin of the present invention is essentially free ofalkylphenols, and particularly nonylphenol, a substance currently underglobal scrutiny as a possible endocrine disrupter. For example, in oneembodiment, phenol is the only phenolic compound used to prepare a resinof the invention. In another embodiment, phenol constitutes at least 98%by weight of the total weight of phenolic compound used to prepare aresin of the present invention. In other embodiments of the invention,phenol constitutes at least 5 wt %, or (in additional embodiments) atleast 10 wt %, or at least 15 wt %, or at least 20 wt %, or at least 25wt %, or at least 30 wt %, or at least 35 wt %, or at least 40 wt %, orat least 45 wt %, or at least 50 wt %, or at least 55 wt %, or at least60 wt %, or at least 65 wt %, or at least 70 wt %, or at least 75 wt %,or at least 80 wt %, or at least 85 wt %, or at least 90 wt %, or atleast 95 wt % of the total weight of the mixture of phenolic compoundsused to form the resin.

Although alkylphenols present health concerns, they are commonly used inthe preparation of rosin-phenolic resins because the alkyl chain impartsneeded aliphatic solvent compatibility to the resin. That is, in orderfor the resin to be commercially viable, it must be soluble in the typesof solvents that are utilized for the target ink, typically eitherlithographic or gravure ink. In these types of ink, the resins must besoluble in aliphatic solvent. In order to achieve this aliphatic solventsolubility, ink resins that utilize rosin and phenolic compoundstypically turn to alkyl phenols because the presence of the alkyl groupis thought to provide or enhance that needed aliphatic solventsolubility.

In a very surprising discovery, the present inventors have found that itis not necessary to include alkyl phenol in a resin-forming reaction, inorder for the resin to have the necessary aliphatic solvent solubility.Instead, phenol itself may be used in lieu of some, or even all, of thealkyl phenol commonly used in resin-forming reactions, so long as theresin-forming components also include fatty acid.

In various aspects of the present invention, phenolic compound is up to50%, or up to 40%, or up to 30%, or up to 20%, or 1-15%, or 1-50%, or1-40%, or 1-30%, or 1-20%, or 1-15%, or 2-50%, or 2-40%, or 2-30%, or2-20%, or 2-15%, or 3-50%, or 3-40%, or 3-30%, or 3-20%, or 3-15%, or4-50%, or 4-40%, or 4-30%, or 4-20%, or 4-15%, or 5-50%, or 5-40%, or5-30%, or 5-20%, or 5-15% of the total weight of the resin-formingcomponents. In additional aspects of the invention, for each of thesepercentage ranges, phenol may constitute 0-100%, or any of the rangesset forth above, of the phenolic compound. In a preferred embodiment,the phenolic component contributes about 5-15 wt % of the total weightof the resin-forming components.

In various aspects of the invention, when phenol constitutes 100% of thephenolic compound present in the reactant components, the fatty acidconstitutes at least 5 wt %, or at least 10 wt %, or at least 15 wt %,or at least 20 wt %, or at least 25 wt %, or at least 30 wt %, or atleast 40 wt % of the reactant components. In other aspects, when phenolconstitutes at least 85 wt % of the phenolic compound present among thereactant components, the fatty acid constitutes at least 5 wt %, or atleast 10 wt %, or at least 15 wt %, or at least 20 wt %, or at least 25wt %, or at least 30 wt %, or at least 40 wt % of the reactantcomponents. In other aspects, when phenol constitutes at least 80 wt %of the phenolic compound present among the reactant components, thefatty acid constitutes at least 5 wt %, or at least 10 wt %, or at least15 wt %, or at least 20 wt %, or at least 25 wt %, or at least 30 wt %,or at least 40 wt % of the reactant components. In other aspects, whenphenol constitutes at least 60 wt % of the phenolic compound presentamong the reactant components, the fatty acid constitutes at least 5 wt%, or at least 10 wt %, or at least 15 wt %, or at least 20 wt %, or atleast 25 wt %, or at least 30 wt %, or at least 40 wt % of the reactantcomponents. In other aspects, when phenol constitutes at least 55 wt %of the phenolic compound present among the reactant components, thefatty acid constitutes at least 5 wt %, or at least 10 wt %, or at least15 wt %, or at least 20 wt %, or at least 25 wt %, or at least 30 wt %,or at least 40 wt % of the reactant components. In other aspects, whenphenol constitutes at least 35 wt % of the phenolic compound presentamong the reactant components, the fatty acid constitutes at least 5 wt%, or at least 10 wt %, or at least 15 wt %, or at least 20 wt %, or atleast 25 wt %, or at least 30 wt %, or at least 40 wt % of the reactantcomponents. In other aspects, when phenol constitutes at least 25 wt %of the phenolic compound present among the reactant components, thefatty acid constitutes at least 5 wt %, or at least 10 wt %, or at least15 wt %, or at least 20 wt %, or at least 25 wt %, or at least 30 wt %,or at least 40 wt % of the reactant components. In each of these manyaspects, the invention optionally provides that Monomer constitutes100%, or 90%, or 80%, or 70%, or 60%, or 50%, or 40%, or 30%, or 20%, or10% of the total weight of the fatty acid.

Aldehyde

The aldehyde of the present invention is reactive with rosin and phenol,to produce crosslinked resinous adducts. Exemplary aldehydes of thepresent invention include, without limitation, formaldehyde,paraformaldehyde, acetaldehyde, glyceraldehyde, butyraldehyde,isobutyraldehyde, benzaldehyde, furfural, and glyoxal.

In various aspects of the present invention, aldehyde is up to 40%, orup to 30%, or up to 20%, or up to 5%, or 2-40%, or 2-30%, or 2-20%, or2-15%, or 3-40%, or 3-30%, or 3-20%, or 3-15%, or 4-40%, or 4-30%, or4-20%, or 4-15%, of the total weight of the components used to from theresin. Paraformaldehyde is a preferred aldehyde to be used as aresin-forming component, and it is preferably used at about 4-12 wt % ofthe resin-forming components, The term “formaldehyde” is used herein toinclude both formaldehyde and paraformaldehyde.

Phenolic Resin

In an optional aspect, the phenolic compound is pre-reacted with thealdehyde, so as to provide a so-called phenolic resin. Thus, phenoliccompound and aldehyde may be added to the resin-forming reaction mixturein the form of a phenolic resin, rather than, or in addition to, the twoindividual reactants.

Polyol

In an optional aspect, the components used to form a resin of thepresent invention further comprise polyol. Polyols of the presentinvention are reactive with acidic moieties via standard esterificationreactions, and are reactive with ester moieties via standardtransesterification reactions, to produce crosslinked resinous adducts.Exemplary polyols include, without limitation, alkylene glycol (such asethylene glycol and propylene glycol), polyalkylene glycol (such aspolyethylene glycol and polypropylene glycol), alkylene triol (such asglycerol, trimethylolethane, and trimethylolpropane), tetrafunctionalalcohols such as pentaerythritol, pentafunctional alcohols such asdimerized trimethylolpropane, or hexafunctional alcohols such asdimerized pentaerythritol, where a preferred polyol of the presentinvention is pentaerythritol.

When polyol is desirably included as a component in a resin-formingreaction, one option is to provide the polyol via a polyester of thepolyol and fatty acid. The polyester, upon transesterification withother reactants, provides not only some or all of the polyol, but alsoprovides some or all of the fatty acid.

Accordingly, the polyol may be introduced to the reaction mixture via anester of the polyol. Likewise, the fatty acid may be introduced to thereaction mixture via an ester of the fatty acid. In one embodiment ofthe invention, polyester is utilized as a reaction component to provideboth polyol and fatty acid. In this embodiment of the invention, thepolyester is preferably a triglyceride, e.g., a vegetable oil.

In various optional aspects of the present invention, polyol (optionallyincorporated into a polyester form) is up to 25%, or up to 20%, or up to15%, or up to 10%, or 1-25%, or 1-20%, or 1-15%, or 1-10%, or 2-25%, or2-20%, or 2-15%, or 2-10%, or 3-25%, or 3-20%, or 3-15%, or 3-10%, or4-25%, or 4-20%, or 4-15%, or 4-10% of the total weight of thecomponents used to form the resin.

α,β-Olefinically Unsaturated Carbonyl Compound

In another optional aspect, the components used to form a resin of thepresent invention further comprise α,β-olefinically unsaturated carbonylcompound. The α,β-olefinically unsaturated carbonyl compound of thepresent invention has an olefinic unsaturation adjacent to the carbonatom of a carboxyl group, i.e., has the —C═C—C(═O)—O— arrangement ofcarbon and oxygen atoms. The α,β-olefinically unsaturated carbonylcompound is reactive with rosin and resin acids, to form adducts. Whenthe α,β-olefinically unsaturated carbonyl compound is maleic anhydride,the adduct between rosin and maleic acid is known as maleic rosin. Whenthe α,β-olefinically unsaturated carbonyl compound is fumaric acid, oran ester of fumaric acid, then the corresponding adduct formed betweenrosin and fumaric acid or a fumarate is known as fumarated rosin.

Suitable α,β-olefinically unsaturated carbonyl compounds include maleicanhydride, fumaric acid, mono (C₁-C₁₂alkyl) ester of fumaric acid,di(C₁-C₁₂alkyl) ester of fumaric acid, acrylic acid, C₁-C₁₂alkyl esterof acrylic acid, methacrylic acid, C₁-C₁₂alkyl ester of methacrylicacid, itaconic acid, and C₁-C₁₂alkyl ester of itaconic acid. Maleicanhydride, fumaric acid and esters of fumaric acid are preferredα,β-olefinically unsaturated carbonyl compounds, with maleic anhydridebeing most preferred.

In various optional aspects of the present invention, α,β-olefinicallyunsaturated carbonyl compound is up to 15%, or up to 10%, or up to 8%,or up to 5%, or 0.1-15%, or 0.1-10%, or 0.1-8%, or 0.1-5%, or 0.5-15%,or 0.5-10%, or 0.5-8%, or 0.5-5%, or 1-15%, or 1-10%, or 1-8%, or 1-5%of the total weight of the resin-forming components. When it is present,the α,β-olefinically unsaturated carbonyl compound is preferably maleicanhydride, and it is preferably utilized at a concentration of 2-4 wt %of the total weight of the resin-forming components.

Alkaline Metal Salt

In another optional aspect, the components used to form a resin of thepresent invention comprise an alkaline metal salt. The metal salt isdesirably present in the reaction mixture as a catalyst for thephenol-aldehyde polymerization. However, the metal salt may also, oralternatively, react with the rosin so as to form resinate, where theterm “resinate” refers to a rosin (which is a carboxylic acid-containingmaterial) in the form of a salt, i.e., a carboxylic acid salt. Thus, inone aspect of the resin composition of the present invention, alkalinemetal salt is combined with rosin, which reacts with carboxylic acidmoiety present in the resin acid components of rosin to produce metalcarboxylate functionalities. Such treatment renders the resultingresinate composition readily soluble in organic solvent, and alsoincreases the melting point of the rosin.

In the present invention, the cation of the alkaline metal salt ispreferably divalent, i.e., carries a charge of +2. Rosin salts ofdivalent cations of zinc, magnesium, and calcium have particularly goodpigment wetting properties, and are preferred in the resinates of thepresent invention. More preferably, the cation of the alkaline metalsalt is divalent magnesium cation. Said salts may be the acetate,carbonate, bicarbonate, formate, hydroxide, oxalate or oxide of a metal.Magnesium salts (including without limitation, magnesium oxide andmagnesium hydroxide) are further preferred.

In various aspects of the present invention, alkaline metal salt is upto about 5%, or 4%, or 3%, or 2%, or 1%, or 0.5% of the total weight ofthe resin composition.

Solvent

One or more inert solvents may be included with, i.e., be in admixturewith, the components used to form a resin of the invention. However,solvent is not construed to be a “component” of the reaction mixture,since it does not participate in the resin-forming reaction.Nevertheless, it may be convenient to include one or more solvents inthe reaction vessel, where hydrocarbons, e.g., xylenes, are an exemplarysolvent.

Process of Manufacture

The present invention provides a resin produced by a process asdescribed herein. The process includes reacting rosin, fatty acid,phenolic compound and aldehyde. These components, and possibly optionalcomponents, are reacted together at elevated temperature so as to form aresin. In order for the components of the reaction mixture to undergo aresin-forming reaction, combinations of the components must be exposedto an elevated temperature in the range of about 80-300° C. At theseelevated temperatures, the components undergo covalent bond-formingreactions with other components, so that some increased molecular weightmaterial is formed.

There are different orders in which the components may be charged to areaction vessel. For example, each of the components may be combinedtogether in a single reaction vessel, and the combination taken toelevated temperature so that the components react with one another toform a resin of the invention. This approach may be termed the “one-pot”reaction process. Alternatively, two or more (but less than all)components may be combined in a single reaction vessel, and thiscombination taken to elevated temperature so that the components reactwith one another to form an intermediate reaction product. Then othercomponents are reacted with the intermediate reaction product, wherethese “other components” may be added individually to the reactionvessel, or two or more of them may be pre-reacted with each other beforethe pre-reaction reaction product is added to the reaction mixture.

For example, the rosin and fatty acid may be combined and heated, duringwhich process these two components will form a fluid mixture. Theresulting reaction mixture can then be combined with the other reactioncomponents (e.g., phenolic compound and/or aldehyde and/orα,β-unsaturated carbonyl compound and/or polyol, as well as otheroptional components such as alkaline metal salt), and the completeadmixture formed either instantaneously, or in stepwise fashion, toallow intermediate reactions to occur with minimal interference. Theresulting reaction mixture may alternatively be combined with a reactionproduct of two or more of phenolic compound, aldehyde, α,β-unsaturatedcarbonyl compound and polyol, in addition to further ingredients. Tocomplete the reaction process, the reaction mixture is taken to elevatedtemperature, typically between about 50° C. and about 310° C.,preferably 120° C. to 310° C., under either normal (atmospheric)pressure or reduced pressure as may be achieved, e.g., using a vacuumsource.

Thus, the invention provides that the components may be reacted with oneanother in any order, at temperatures within the range of 50-310° C., toobtain a resin of the invention. The present invention also providesthat after reacting together components in a reaction mixture, anadditional amount of one or more of said components may be added to saidreaction mixture and further reacted together, a procedure commonly donein commercial resin production. It should be recognized that the samecomponents (in terms of quantity and identity) may form resins withdifferent properties, depending on the precise manner in which thecomponents are reacted together. However, determining these propertiesis well within the skill of the ordinary artisan.

Elevated reaction temperatures are selected in view of the followingpoints. The reaction temperature must be high enough that the contentsof the reaction vessel are sufficiently fluid to allow those contents tobe stirred. Higher temperatures are generally preferred for reasons ofeconomy, in order to provide a faster rate of reaction. However, thereaction temperature should not be so great that the reaction componentsboil out of the reaction vessel. Nor should the temperature be so greatthat decomposition of the reaction components or reaction productsshould occur. The term “elevated” is used to indicate that standard roomtemperature, i.e., ca. 230° C., will not be hot enough to provide thefluid state needed for the reactants. At a minimum, the elevatedreaction temperature must be about 50° C., and is preferably at least100° C. A lower temperature may be utilized if a solvent is includedwithin the reaction vessel.

The resin-forming reaction mixture may, and typically will containwater; furthermore, the resin-forming reaction generates water as abyproduct of the covalent bonds that are formed between members of thereaction components. In order to drive the reaction toward completion,this water should be removed from the reaction or product mixture. Inthe absence of vacuum or azeotrope formation, a reaction temperature ofat least 100° C. is needed in order to distill water away from thereacting components. Thus, at least during the initial stage(s) ofresinate or ester formation, the reaction temperature is desirably setto about 100-190° C. While a higher initial reaction temperature may beused, the consequence may be water generation at a rate that is muchgreater than water removal may be conveniently accomplished.

In order to drive the reaction to completion, removal of water may beenhanced through addition of an organic solvent that forms a low-boilingazeotrope with water, and/or the addition of a light vacuum on thereaction vessel. To provide a low-boiling azeotrope, an organic solventthat forms an azeotrope with water, e.g., toluene or xylene, can beadded to the reaction vessel, and then removed by distillation, undernormal pressure. However, in one aspect of the invention, azeotropicdistillation is not used to remove water from the resin.

The reaction components are maintained at about 120-310° C. until thereaction is considered finished. Reaction progress is convenientlymonitored by periodically taking samples of the reaction mixture andmeasuring one or more relevant properties of the sample. For example,initially the acid number of the reaction mixture may be as high asabout 300. The acid number will gradually fall as the resin-formingreaction proceeds. Melting point (softening point), melt viscosity,solution viscosity and/or cloud point measurements may also be made tomonitor reaction progress.

The amounts of the various reactants are preferably selected so that thereaction mixture does not form a gel during the heating process. This isparticularly important when the reaction mixture containsmultifunctional reactants, e.g., maleic anhydride and pentaerythritol.However, gelling can also occur when only rosin, fatty acid, aldehydeand phenolic compound are used to form the resin. The Examples containedherein provide several formulations that do not gel. For example, amixture of about 60 wt % gum rosin, ca. 15 wt % phenol, ca. 15 wt %paraformaldehyde (91%), ca. 10 wt % Monomer, and a trace (ca. 0.5 wt %)magnesium oxide can be used to provide a fluid (when molten), ratherthan a gelled, resin. As another example, a mixture of about 45 wt % gumrosin, ca. 20 wt % tall oil rosin, ca. 8 wt % phenol, ca. 5 wt %paraformaldehyde (91%), ca. 10 wt % Monomer, ca. 2 wt % maleicanhydride, ca. 10 wt % pentaerythritol, and a trace (ca. 0.1 wt %)magnesium oxide can be used to provide a fluid (when molten), ratherthan a gelled, resin.

If a reaction mixture does get to an undesirable extent, then anadjustment should be made in the amount of one or more of the reactioncomponents. One of ordinary skill in the art is familiar with theability of some mixtures of rosin, fatty acid, phenolic compound andaldehyde, plus (optionally) maleic anhydride and polyol, to form agelled mixture, and is readily able to adjust the formulation as neededto reduce the gelled component of the resin to an acceptably low level.To this end, a statistical design of experiments may be utilized tooptimize a formulation for a particular end-use, e.g., gravure vs.lithographic ink resin. Since the resins of the invention preferablyhave a relatively high molecular weight, and accordingly have arelatively high solution viscosity, successful resin formulations areoften close to those resin formulations that yield an undesirable amountof gelled resin.

Thus, in one aspect, the present invention provides a resin produced bya process, where the process includes reacting the following components:rosin, fatty acid, phenolic compound and aldehyde. In another aspect,the components include α,β-olefinically unsaturated carbonyl compound.In another aspect, the components included polyol. In another aspect,the components include both α,β-olefinically unsaturated carbonylcompound and polyol. The components are reacted at elevated temperatureso as to form a resin, preferably a gel-free resin.

In another aspect, the present invention provides a resin produced by aprocess, where the process includes reacting the following components:rosin, monocarboxylic acid, phenolic compound, aldehyde, and polyol.These components are reacted at elevated temperature so as to form aresin. An exemplary product is formed by the process of reacting rosin,fatty acid and phenol at elevated temperature, optionally with additionof a reaction catalyst, followed by addition of paraformaldehyde,followed by the addition of polyol. However, other orders of combinationof the components may also be employed to prepare a product of thepresent invention.

In another aspect, the present invention provides a resin produced by aprocess, where the process includes reacting the following components:rosin, fatty acid, phenolic compound, aldehyde, α,β-olefinicallyunsaturated carbonyl compound, and polyol. These components are reactedat elevated temperature so as to form a resin. An exemplary product isformed by the process of reacting rosin, fatty acid and phenol atelevated temperature, optionally with addition of a reaction catalyst,followed by addition of paraformaldehyde, followed by the addition ofα,β-olefinically unsaturated carbonyl compound, followed by the additionof polyol. However, other orders of combination of the components mayalso be employed to prepare a product of the present invention, asdescribed below.

In a preferred aspect, the process for preparing a resin of the presentinvention comprises the ordered steps of:

a) heating rosin in a reaction vessel, optionally at about 140-180° C.,optionally in admixture with monocarboxylic acid and phenolic compound,until a homogeneous molten liquid is formed;

b) further charging the reaction vessel with, if not present,monocarboxylic acid and phenolic compound, then allowing the reactionmixture to react, optionally at about 100-140° C., optionally for up toabout 60 minutes;

c) further charging the reaction vessel with aldehyde, then allowing thereaction mixture to react, optionally at about 100-180° C., optionallyfor up to about 300 minutes;

d) further optionally charging the reaction vessel with α,β-olefinicallyunsaturated carbonyl compound, then allowing the reaction mixture toreact, optionally at about 120-250° C., optionally for up to about 150minutes;

e) further optionally charging the reaction vessel with polyol, thenallowing the reaction mixture to react, optionally at about 120-310° C.,optionally for up to about 48 hours.

In an optional aspect, the process for preparing a resin furthercomprises charging the reaction vessel with alkaline metal salt whereinthe cation of said salt is divalent. The salt may be added afterformation of the homogeneous molten liquid. Thus, the present inventionprovides that for each of the processes and reaction mixture describedherein, metal salt may be added to the components to provide a resin ofthe present invention.

Resin Properties

The resins of the present invention may be characterized by theirproperties, which include acid number, melting point, molecular weightdistribution and solubility. These properties are routinely measured forink resins, and thus one of ordinary skill in the art is very familiarwith techniques to measure these properties. Nevertheless, a briefdescription of suitable techniques to measure certain of theseproperties is provided here.

Acid number is measured by dissolving a known weight of resin (e.g., 1gram) into an organic solvent (e.g., toluene is a typical solvent,however a 1:2 ratio weight ratio of isopropanol:toluene may be used iftoluene alone does not dissolve the resin), and then titrating ameasured amount of methanolic potassium hydroxide (e.g., 0.1 N methanolKOH) solution into the resin solution. The titration is complete when apH of about 7 is attained. This endpoint can be seen by includingphenolphthalein in the solution, where the endpoint occurs when a faintpink color persists for at least 15 seconds. The acid number of theresin is equal to the amount of KOH, in mg, which was used in thetitration, divided by the weight of resin, in grams, in the sample thatwas titrated. In other words, acid number is equal to the mg of KOHneeded to neutralize 1 gram of sample.

In various optional aspects of the present invention, the acid number ofthe resin composition is less than about 70, or less than about 60, orless than about 50, or less than about 30; or about 1-70, or 1-50, or1-60, or 1-50, or 1-30, or 5-50, or 5-40, or 5-30, or 10-70, or 10-60,or 10-50, or 10-40, or 15-70, or 15-60, or 15-50, or 15-40. For a resinintended for a lithographic ink formulation, the acid number of theresin is preferably about 20. When the resin is intended for a gravureink formulation, the resin preferably has an acid number of about 45.

Melting point, which may also be referred to as “softening point,” maybe measured by the so-called ‘ring and ball’ method, which is thesubject of ASTM E28. Alternatively, a softening point value may beobtained using a softening point instrument from Mettler Laboratories(Hightstown, N.J., USA). The melting point values described and reportedherein were obtained using a Mettler FP90/FP83HT Cup and Ball apparatus,according to the following procedure: A 2.80 mm bottom orifice samplecup is filled with the molten resin to be tested. The excess resin isremoved to give a flat surface. The solid resin should be free ofbubbles. The sample cup is placed in the cartridge with the lead ball(3.4±0.2 gram) centered on top of the sample and the cartridge is placedin the furnace. The following conditions are used: start temperature is20-25° C. below the expected softening point, heating rate of 1.5°C./min. Results reported in ° C. According to this procedure, a resin ofthe present invention preferably has a softening point in excess of 120°C., e.g., 120-200° C., and more preferably has a softening point ofabout 145° C.

A resin of the present invention may be characterized in terms of itsmolecular weight, where molecular weight is conveniently measured usinggel permeation chromatography (GPC). GPC analysis may be performed usinga Waters model 515 pump (Waters Instruments, Plymouth, Minn., USA;www.wtrs.com), Waters model 717 auto injector and Waters 410differential refractive index (RI) detector. The components were elutedwith tetrahydrofuran (THF) through a row of 3 Polymer Labs (PolymerLaboratories, Amherst, Mass., USA; www.polymerlabs.com) mixed-B GPCcolumns. Molecular weight was determined by comparison of retentionstimes to a column calibrated with polystyrene standards. Under theseconditions, a preferred resin of the present invention has a peakmolecular weight within the range of 30,000-500,000, more preferablyabout 200,000.

A resin of the invention may be characterized in terms of its solutionform. In other words, a solution of the resin in a suitable solvent isprepared, and this solution is characterized in order to evaluate thequality of the resin. The solution may be referred to as a varnish,where the varnish may be used to prepare an ink. The following proceduremay be used to prepare a solution (varnish) containing a resin of thepresent invention, where the varnish itself is an aspect of the presentinvention. The device used in this procedure is called a “Thermotronic”,and it is available from Testprint, Inc. (Cherry Hill, N.J., USA;www.testprint.com).

The resin is crushed under mechanical force, and the crushed resin and atest solvent are weighed into a metal Thermotronic test tube for a totalsample size of 50 grams. The varnish is typically prepared at a resinsolids concentration of 35-50 wt %, preferably about 45 wt %. The tubeis placed in the Thermotronic and a PT-100 temperature probe isinserted. The Thermotronic controllably heats the solution using thefollowing parameters: stirring speed (RPM) 120; heating rate (°C./minute) 35; top temperature (° C.) ca. 180-230 C; hold time (minutes)ca. 2-10; cooling rate (° C./minute) 20. Suitable solvents for thispurpose include M47, TXIB, ARLO, and N40HT, where M47 is MAGIESOL™ M-47,a “technical white oil,” from Magie Brothers, Franklin Park, Ill.,presently a division of Pennzoil Products Company; TXIB is a plasticizerester of the chemical name 2,2,4-trimethyl-1,3-pentanediol diisobutyratesold by Eastman Chemical, Kingsport, Tenn.; ARLO is Alkali RefinedLindseed Oil, a commodity chemical; and N40HT is a specific hydrotreatednaphthenic petroleum oil (Chemical Abstract Service Registry No.64742-53-6), where many members of this family of oil are commerciallyavailable (see, e.g., San Joaquin Refining Co., Inc. Bakersfield,Calif., USA). Two other suitable solvents are the printing inkdistillates known as PKWF® and PRINTOSOL® solvents, both available fromHaltermann Products (a subsidiary of the Dow Company, Channelview, Tex.,USA; www.haltermann.com). PKWF® 6/9 AR is a low aromatics (<=1%)hydrocarbon having a distillation range of 260-290° C. at 1013 kPa (perASTM D 4052). The solvents may be blended together if desired, e.g., 1:1M47 and TXIB may be used as the solvent.

Inks and Varnishes

The present invention provides solutions of the ink resins of thepresent invention, including solutions intended to be components of inkformulations, where these later solutions are commonly known asvarnishes. Varnishes useful in gravure and lithographic inks may becharacterized in terms of their viscosity, tan delta, and cloud point,among other properties known to one of ordinary skill in the art.Varnishes for evaluation purposes, such as for rheological evaluation,may be prepared using the Thermotronic device described above.

Rheology flow measurements can be made on a varnish of the presentinvention. This measurement can be performed using a TA Instruments (NewCastle, Del., USA; www.tainst.com) AR-1000N rheometer in flow mode at25° C. using a 4 cm 1° cone set at the geometric gap. A shear rate of 25s⁻¹ is applied for 1 minute with 50 measurement points collected. Thefinal measurement point is taken as the flow viscosity and is reportedin Pa·s. Under these conditions, a 45 wt % PKWF 6/9 AR solution of aresin of the present invention preferably has a flow viscosity of 0.1 to450 Pa·s., or 0.5 to 450 Pa·s., or 5 to 450 Pa·s., or 0.1 to 150 Pa·s.,or 0.5 to 150 Pa·s., or 5 to 150 Pa·s. In one aspect, a varnish of thesolution has a flow viscosity of about 5 to 150 Pa·s. for a resinintended for a lithographic ink. In one aspect, the flow viscosity ofthe varnish is 20-80 Pa·s.

Rheology frequency sweep measurements may be used to determine the tandelta of a varnish of the present invention. This measurement is made bydetermining the rheology of the resin solution with a TA InstrumentsAR-1000N rheometer in oscillation mode at 25° C. using a 4 cm 1° coneset at the geometric gap. A frequency of 1 Hz is applied using acontrolled strain of 0.10. A temperature sweep is made between 10° C.and 60° C. over 15 minutes. Tan Delta, G′ (Dynes s⁻¹) and G″ (Dynes s⁻¹)are reported at 23° C. A varnish of the present invention preferably hasa tan delta of greater than 1.5, but more preferably has a tan delta ofless than 5.

Cloud point may be measured in resin solutions according to standardmethods ASTM D97 and SCAN T5:67. The present inventors prefer todetermine cloud point using a Chemotronic Cloud Point Tester, availablefrom Testprint, Inc. (Cherry Hill, N.J., USA; www.testprint.com). Tomeasure cloud point, a sample of the resin is mechanically crushed, and2.0 g of crushed resin and 18.0 g of the test solvent are weighed into aChemotronic glass test tube. The tube is then placed in the Chemotronicand a PT-100 temperature probe is inserted. The Chemotronic heats thesolution, cools automatically and reports cloud point in degrees C. Thefollowing parameters are used for all solvent systems: heat to toptemperature of 230° C. at a typical rate of 40° C./min, hold at 230° C.for 2 minutes, then cool at a typical rate of 40° C./minute.

Under these conditions, a clear solution is preferably produced at atemperature within the range of 25-180° C. For lithographic printing,the cloud point of the resin may be used as a guide to determine thetype of ink the resin is well suited for. For example, if the cloudpoint is low, i.e., ca. 25° C., then the resin has very good aliphaticsolubility and may be used for pigment wetting. If the cloud point is inthe mid-range, i.e., ca. 50-150° C., the resin may be particularlyuseful in heat set lithographic inks. If the cloud point is high, i.e.,ca. 180° C., the resin may be particularly useful in inks for sheet fedlithography. For gravure printing, the cloud point of the resin is notparticularly critical, and cloud points in the range of 75-180° C. areacceptable, where these cloud points are measured at ca. 10 wt % solidsin a solvent. In one aspect, the resin of the present invention iscompletely soluble at 180° C. in mineral oil at a 10% resin solidsconcentration.

The present invention also provides an ink suitable for printing, suchas gravure or lithographic printing. In gravure printing, a cylinderonto which is engraved or etched the image to be printed is rolleddirectly into ink and transferred directly to the substrate that acceptsthe printed image. Gravure printing is a very common commercial mode ofprinting, and is well known to one of ordinary skill in the art. Gravureprinting is often used in printing on substrates such as magazine stock,metal foils, plastic films, and paper cartons.

A gravure ink of the present invention contains a resin as disclosedherein, in addition to a solvent, a colorant and optionalperformance-enhancing additives. The inventive resin can be used aloneor in combination with co-resins. Suitable co-resins include commonlyknown co-resins such as, without limitation, rosin modified maleic andphenolic esters, hydrocarbon resins and alkyds. Owing to the lack ofintermediary rollers and/or cylinders utilized in gravure printing, theink used in gravure printing must be of very low viscosity and finelyground so as to reduce the amount of scratching imparted to the engravedor etched cylinder; yet, because of the relative absence ofsolvent-sensitive (i.e., rubber-composed) moving parts needed for saidprinting process, a wide range of solvents are acceptable for use ingravure printing. Suitable solvents include, without limitation, mineraloils, aromatic and ester solvents. Suitable colorants include flushedcolor, dry pigments and soluble dyes. Additives can include, withoutlimitation, waxes, wetting agents, and plasticizers. In addition to thematerials noted above, the ink additionally may contain any number ofoptional components, where the optional component(s) provide forimprovements in the performance of the ink. Ink performance propertiesinclude color strength, gloss, scuff resistance, block resistance,misting, open time on press and many other properties.

The resins of the present invention are particularly useful as let downvehicles for gravure inks, e.g., publication gravure inks. Thus, apigment dispersion may be prepared using a pigment and a solutionresinate, where solution resonates are well known, commerciallyavailable products currently used for pigment grinding. After thepigment dispersion has reached a desired state, e.g., a desired averagepigment particle size, the dispersion is diluted with a letdown vehicle.In addition to diluting the colorant, the letdown vehicle impartsvarious desirable properties to the ink. Desirable properties includegloss and scuff resistance. The rosin phenol resin of the presentinvention, dissolved in a suitable solvent such as toluene, can be usedas a component of such a letdown vehicle. The rosin phenolic resin willtypically be present at about 30-35% solids in such a vehicle. In oneaspect the present invention provides a phenolic resin as describedherein, in a varnish form.

Lithographic printing is a process whereby ink is transferred by rollingonto one or several additional cylinders before transferring ink ontothe substrate, in contrast to gravure printing, where ink is directlytransferred to the substrate. The lithographic printing process is suchthat ink is run in combination with an aqueous solution (known in theart as a fountain solution), the purpose of the fountain solution beingto wet the parts of the substrate that do not receive ink. Lithographicprinting is also a very common commercial mode of printing, used inprinting on substrates such as packaging material, and is well known toone of ordinary skill in the art.

Lithographic printing is divided into two major types: sheet-offset, orprinting on individual substrate sheets; and web-offset, or printing oncontinuous rolls of substrate. Each of these two major types is furtherdivided into subclasses based on the mechanism of ink drying. Hence, theproperties of a desirable lithographic ink binder are largely dependenton the specific type and subclass of printing employed. Some resinproperties commonly desirable for essentially all types of lithographicprinting include high melting point, high viscosity, good solubility inhigh-boiling low-solvency aliphatic solvents, good pigment wetting, andlow pigment reactivity.

In one aspect, the resins of the present invention demonstrateself-gelling behavior. In other words, they do not require the presenceof metal salt in order to gel a hydrocarbon solvent. Whether a resin isself-gelling can be determined using a viscometer, which can measure theviscoelasticity of a mixture of resin and solvent. In order to determineits viscoelasticity, a solution of resin and mineral oil is prepared bymixing the components for 30 minutes at 180° C. in a weight ratio ofresin:mineral oil of 1:1.5. The mineral oil should have a boiling rangeof 240-270° C. and an aniline point of 72° C. (standard mineral oil PKWF 4/7, supplier: Haltermann). This mixture is cooled to roomtemperature, and the tan delta of the solution is measured using aviscometer. For instance, an oscillating rotary viscometer (RV 20/CV 100apparatus from Haake using measuring device (cone) PK 20 at 23° C., adeflection angle of 10°, a frequency sweep of 0.05 to 5 Hz, and anangular velocity range (omega) of 1-10 s⁻¹ gives tan delta value of <5for a self-gelling resin.

Printing ink may be prepared by adding colorant (flush color, drypigment or soluble dyes), additives and additional solvent to a letdownvarnish comprising a resinate composition of the present invention.Flush color is a form of pigment where the solvent used during thepigment manufacturing process (water) has been replaced by a hydrocarbonor oil based varnish. Such a varnish can contain the inventive orconventional resins, resinates, or a combination of both. Finished inkmay be prepared by adding the flush color and the letdown varnish whilemixing at low shear. The mixture can be passed through a bead mill orshot mill to further reduce pigment particle size and improve final inkproperties. Soluble dyes can be added with little or no additionalenergy to impart color to the system. Additional varnish or solvent canbe added to adjust tack, flow and viscosity to reach targetspecifications and then additives are blended in.

The following are some optional components may be included in an ink ofthe present invention. Blown Castor Oil (BCO) may be included at a levelof 1-3 wt % in order to reduce the water pickup of the ink. Soy bean oil(SBO) is often used in inks in order to reduce their tack, and toincrease the flowability of an ink, where a typical concentration is1-10 wt %. Tung oil may be included in an ink formulation at aconcentration of about 5-15 wt % in order increase the setting speed ofan ink. Tung oil may also increase the hardness of the dried ink. Tungoil, like SBO, can also increase the flowability of an ink, and reduceits tack. Alkali Refined Linseed Oil (ARLO) is extracted from the seedof the flax plant, and consists largely of linolenic acid. ARLO can beused for cutting tack and body, increasing flow of overly “short” inks,and to enhance the film integrity of inks that contain metallic driersthat can react with ARLO. The addition of Gelled Linseed Oil (GLO) to anink is a convenient way to reduce the tack of a heavy ink, particularlysheetfed or web offset inks. Each of these oils is a commodity chemicaland readily available from many commercial suppliers.

One of ordinary skill in the art is familiar with preparing printinginks using either flush color, dry pigment or soluble dyes, and mayadopt other procedures for preparing such a printing ink using a resinof the present invention.

EXAMPLES

The invention is illustrated in more detail by the following examples.In the following examples, chemicals were of reagent grade unless notedotherwise, and were obtained from commercial supply houses such asAldrich Chemical Co. (Milwaukee, Wis.). SYLVAROS™ 85 tall oil rosin,SYLFAT™ 2S tall oil fatty acid, and CENTURY MO6™ Monomer are availablefrom Arizona Chemical (Jacksonville, Fla.). Chinese gum rosin isavailable from sources such as BFB Enterprises (Panama City Beach,Fla.). Test oils 6/9 and 6/9 AR are mineral oils available fromHaltermann Products (Channelview, Tex.). When a value is recited such as“45% AR”, this refers to a solution of the resin in 6/9 AR test oil, at45 wt % solids (100× weight of resin divided by the sum of the weightsof the resin and the solvent).

Example 1 Rosin Modified Phenolic Ester

As summarized in TABLE 1, a reaction vessel was charged with Chinese gumrosin, CENTURY MO6™ Monomer, and phenol, and heated to about 150-170° C.After the mixture was molten, the vessel was further charged withmagnesium oxide catalyst (dispersed in about 15 grams xylene), and theresulting admixture was cooled to about 110° C. The reaction vessel wascharged with 91% paraformaldehyde, and the resulting admixture wasrefluxed at about 120° C. for about 90 minutes, before heating to about270° C. (@ 35° C./hr) to allow removal of condensed water and drive thereaction to completion. TABLE I Composition Of Rosin Monomer PhenolicResin CAS No. Component Weight Percent 8050-09-7 Chinese Gum Rosin 58.16108-95-2 Phenol 14.54 30525-89-4 Paraformaldehyde, 91% 15.31 68955-98-6CENTURY MO6 ™ Monomer 11.63 1309-48-4 Magnesium Oxide 0.36 Total charge(grams): 825.36 Final Softening point (° C.): 155 Final Acid Number (mgKOH/g): 56

Examples 2-4 Rosin Modified Phenolic Ester

These examples describe the preparation of rosin modified phenolicesters suitable for use in lithographic varnish manufacture, accordingto the weight percentages indicated in TABLE 2.

A reaction vessel was charged with Chinese gum rosin, tall oil rosin,CENTURY MO6™ Monomer, and phenol, and heated to about 150-170° C. Aftermelting the rosin, the vessel was further charged with magnesium oxidecatalyst (dispersed in about 10 grams xylene), and the resultingadmixture was cooled to about 110° C. The reaction vessel was thenfurther charged with 91% paraformaldehyde, the resulting admixture wasallowed to reflux at about 110-120° C. for about 90 minutes, beforeheating to about 155° C. to allow removal of condensed water. Thereaction vessel was then further charged with maleic anhydride, and theresulting admixture was heated to 210° C. The reaction vessel was thenfurther charged with mono-pentaerythritol, and the resulting admixturewas heated to about 270° C., to allow removal of water produced fromesterification. The reaction product was sampled hourly at 270° C. forviscosity in mineral oil and cloud point from mineral oil solution.Optionally, the reaction mixture was held at about 150° C. overnight,before reheating the mixture to 270° C. and proceeding with sampling asabove. Upon reaching the desired level of viscosity and solids, thereaction mixture was cooled to about 250° C. and discharged. TABLE 2Composition Of Rosin Modified Phenolic Ester Weight Percent CAS No.Component Ex. 2 Ex. 3 Ex. 4 8050-09-7 Chinese Gum Rosin 43.85 47.48 44.28052-10-6 SYLVAROS ™ 85 Tall 18.79 20.35 19.0 Oil Rosin 108-95-2 Phenol8.50 5.52 8.6 30525-89-4 Paraformaldehyde, 91% 6.94 4.50 7.0 68955-98-6CENTURY MO6 ™ 11.33 7.01 10.6 Monomer 1309-48-4 Magnesium Oxide 0.150.11 0.1 108-31-6 Maleic Anhydride 1.22 3.78 1.2 115-77-5Mono-Pentaerythritol 9.22 11.26 9.2 Total charge (grams): 2472 1141.61225 Final Softening Point 130 150 138 (° C.): Final Viscosity 45% AR37.9 32.2 42.2 (Pa · s): Rheology Tan delta, 5.186 n.d. 5.522 23° C.,45% AR: Final Cloud Point (° C.): 109 126 119 Final Acid Number 19.320.3 22.3 (mg KOH/g):

Example 5 Rosin Modified Phenolic Ester

Following essentially the same procedure as set forth in Examples 1-4,the reactants of TABLE 3 where charged to a reaction vessel. TABLE 3Resin-Forming Reaction Mixture Weight Weight % Gum Rosin 487.8 g 43.1% Tall Oil Rosin   209 g 18.5%  Monomer   144 g 12.7%  Phenol  94.5 g 8.4%MgO  1.6 g 0.2% Paraform 86.2 7.6% Maleic Anhydride  7.8 g 0.7%Pentaerythritol 100.5 g 8.8% Total Charge 1,131.4 g   100% 

The resin of Example 5 had a cloud point as measured at 10 wt % in testoil of 105° C., a viscosity at 23° C. as measured for a 45 wt % solutionin test oil of 26.2 Pascal, and an acid value of 20.6.

All of the above U.S. patents, U.S. patent application publications,U.S. patent applications, foreign patents, foreign patent applicationsand non-patent publications referred to in this specification and/orlisted in the Application Data Sheet, are incorporated herein byreference, in their entirety.

From the foregoing it will be appreciated that, although specificembodiments of the invention have been described herein for purposes ofillustration, various modifications may be made without deviating fromthe spirit and scope of the invention. Accordingly, the invention is notlimited except as by the appended claims.

1. A process for preparing a resin, the process comprising reactingcomponents at elevated temperature, the components comprising rosin,fatty acid, aldehyde and phenolic compound, where phenol constitutes atleast 25 wt % of the phenolic compounds.
 2. The process of claim 1wherein phenol constitutes at least 35 wt % of the phenolic compounds.3. The process of claim 1 wherein phenol constitutes at least 55 wt % ofthe phenolic compounds.
 4. The process of claim 1 wherein the rosinconstitutes up to 85 wt % of the components.
 5. The process of claim 1wherein the fatty acid constitutes up to 65 wt % of the components. 6.The process of claim 1 wherein the aldehyde constitutes up to 40 wt % ofthe components.
 7. The process of claim 1 wherein phenolic compound(s)including phenol constitute up to 50 wt % of the components.
 8. Theprocess of claim 1 wherein the fatty acid component comprises Tall OilFatty Acid (TOFA).
 9. The process of claim 1 wherein the fatty acidcomponent comprises Monomer.
 10. The process of claim 1 wherein thealdehyde component comprises formaldehyde.
 11. The process of claim 1wherein the rosin component comprises gum rosin.
 12. The process ofclaim 1 wherein the components further comprise polyol.
 13. The processof claim 12 wherein the polyol component constitutes up to 15 wt % ofthe components.
 14. The process of claim 1 wherein the componentsfurther comprise an α,β-unsaturated carbonyl compound.
 15. The processof claim 14 wherein the α,β-unsaturated carbonyl compound constitutes upto 8 wt % of the components.
 16. The process of claim 1 wherein theresin is self-gelling in mineral oil at resin:mineral oil weight ratioof 1:1.5.
 17. The process of claim 1 wherein the resin is completelysoluble in mineral oil at 10% solids at 180° C.
 18. The process of claim1 wherein the resin has a softening point in excess of 120° C.
 19. Theprocess of claim 1 wherein a 45 wt % solution of the resin in ahydrocarbon solvent has a flow viscosity at 25° C. of 0.1 to 150pascal-seconds.
 20. The process of claim 1 wherein the resin is suitablefor use as a lithographic ink resin.
 21. The process of claim 1 whereinthe resin is suitable for use as a gravure ink resin.
 22. The process ofclaim 1 wherein azeotropic distillation is not used to remove water fromthe resin.
 23. The process of claim 1 wherein an inert organic solventcapable of azeotropic distillation of water at the elevated temperatureis not used as an entraining agent for azeotropic distillation of water.24. A resin prepared by the process of any of claims 1-23.
 25. A varnishcomprising a resin prepared by the process of any of claims 1-24, and asolvent.
 26. The varnish of claim 25 wherein the solvent is ahydrocarbon.
 27. A lithographic ink comprising a resin of claim
 24. 28.A gravure ink comprising a resin of claim
 24. 29. A process forpreparing a resin, the process comprising reacting components atelevated temperature, the components comprising rosin, aldehyde,phenolic compound and fatty acid, where the fatty acid constitutes atleast 30 wt % of the components.